The participatory democracy framework. A generator and multiple gems made with Ruby on Rails
Consul Democracy - Open Government and E-Participation Web Software
Optimal execution and market making, implemented four times over from the same pinned contract: **Almgren-Chriss (2000)** discrete optimal execution, **Avellaneda-Stoikov (2008)** finite-horizon market making, and execution analytics (Perold implementation-shortfall decomposition, participation rate, a tiny native OLS for market-impact estimation).